Production of ferric salts.



ooassa s zes straits l'rnn rricn ANSC N G. BETTE, 0F TXEOY, NEW YORK.

PRODUCTION OF FEERIG SALTS.

ferrous salts of polybasic acids, for example ferrous sulfate andferrous tluosilicate.

A further objectto provide a process for the purpose mentioned which canbe practical with apparatus of the simplest possible character.

In the production of such salts by elec trolytic methods one of thechief difliculties encountered is polarization at the anode, withresulting loss of eiliciency and destruction of the carbon anodesthrough increased resistance to the electrolyzing current, and in aprior patent granted to me November 7, 1905, No. 503,543, I have described a process in which the diilioulty referred to is practicallyovercome by pro ducing' large relative movement between the anode andthe electrolyte, so to facilitate the continuous oxioation of theferrous salt by the liberated anions. I have discovered, however,thatsatistactory results can be oblained without such relative motion itthe solution is el'ectrolyzedat. a high tempera-. ture. For example, ita solution of ferrous sulfate and sulfuric acid is electrolyzed at aten'iperature of from 50 to 100 Q, using a carbon anode, theelectrolysis proceeds without appreciable polarization at the anode andwithout evolution of gases, and

a large percentage of the ferrous is-conrerlcd into ferric salt, withvery lughcurrent OlllCltilCy. Just what is the lowest ten .peratureperinissil'ile depends on circumstanceasueh as current density at theanode and the percentage of acid and of ferrous iron in the solution. Attemperatures of 50? (l. and below l have not been able to oxidize ironsuccessfully Witlmutkeeping: up a relalive motion between the anode andthe solution:

As a specific instance of the practice of my method I may hire thefollowing: A solution containing; grains iron as :terric Specificationof Letters Patent.

Application filed January '7, 1909. Serial Patented Sept, Iii 31910.

Sulfate, 1.0 grams iron as 'i'crrous sulfate, 1.3"?) grams copper ascopper sulfate, and about 4 grams free sulfuric'acid per 100 cc., can beelectrolyzed at a temperature of 80 (1., with a graphite anode, at ananodecurrent density of 11 ainperes per square foot, without showingmore than slight extra polarization beyond that necessary for theformation of ferric sulfate. The same solution at a temperature of 70(1., with a current density of 8.5 aniperes per square foot, shows anextra polarization of half a volt or over, which still greater at lowertemperatures. With a current density of 1&5 ainperes per square footthere is an extra polarization of over half a volt at 84 (3., showingthe necessity of using a still higher temperature at the higher currentdensity. By circulating the electrolyte, or moving the anode, asdescribed in my prior patent before referred. to, a lower temperaturemay be used. in fact especially good results are obtained by employingconsiderable relativeniotion and some bea t, the relative motionnecessary being less as he te1nperature rises,

What I claim is:

l. The process of oxidizing in solution ation sufficiently high, asdescribed, to sub;

stantially prevent the evolution of oxygenvcontaining at the anode, asset forth.

The process of oxidizing in solution a ferrous salt of a polybasic acidto a ferric salt, which consists in eleetrolyzing the solution with aninsoluble anode while maintaining the said solution at a temperaturehigher than 50 (L, as set forth 3. The process of oxidizing in solutiona ferrous salt of a polybasic acid to aferric salt, which consists inelectrolyzinp; the solution with an insoluble anode while main tainingthe said solution. at atemperature between 50 and 100 (1 approximately,as set forth. v

4. The process of oxidizing ferrous sulfate to ferric sulfate, whichconsists in electrolyzinp; a solution containing ferrous sulfate with aninsoluble anode, at a temperature sulliciently high, as described, tosubstantially prevent the evolution of oxygencontaining gas at theanode, as set forth.

fate, copper sulfate, and free sulfli'i'ic acid,

while maintaining the solution a? :i tcmpernture between 50 and 100 LL,as sot forth.

In testimony whereof I afl'ix my signature in the presence of twosubscribing wit nesses.

ANSON G. BETTS.

-Witnesses r BENJAMIN S'iuinmioK, AUDLEY A. MCQUIDE.

